Grace's Guide

British Industrial History

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Rolls-Royce Engines: Eagle

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Note: This is a sub-section of Rolls-Royce

The name 'Eagle' was used by Rolls-Royce for a number of engines, most famously the first, the Eagle V12 aero engine developed during the First World War, and used to power a number of military aircraft.

The first Eagle aero engine was a liquid cooled V12 engine with the cylinders inclined at 60 degrees and the valves driven by overhead camshafts. It first ran in 1915. Bore and stroke were 4.5 inches by 6.5 inches (115 x 165 mm) giving a 20 litre capacity. The whole engine weighed 408 kg (900 lb) producing 360 hp (268 kW) at 1,800 rpm.

Production ran until 1928 by which point 4,681 had been built.

There is an example of this engine in the London Science Museum.

General characteristics

  • Type: 12-cylinder liquid-cooled 60° Vee aircraft piston engine
  • Bore: 4.5 in (115 mm)
  • Stroke: 6.5 in (165 mm)
  • Displacement: 1,220 in³ (20 L)
  • Dry weight: 900 lb (408 kg)


  • Valve-train: Overhead camshafts
  • Supercharger: none
  • Cooling system: Liquid-cooled


  • Power output: 360 hp (268 kW) at 1,800 rpm
  • Specific power: 0.32 hp/in³ (13.4 kW/L)
  • Power-to-weight ratio: 0.40 hp/lb (0.66 kW/kg)

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